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Field study of local exhaust hood performance, revised final report.

Environmental and Occupational Health Sciences, School of Public Health, University of Illinois, Chicago, Illinois 1996 Feb; :1-205

Link

NIOSHTIC No.

00235392

Abstract

A field study was performed to determine the performance of slot hoods used to exhaust vapor degreasers. Sixteen degreasers were used in the study. The objectives were to measure capture efficiency of local exhaust hoods used to control vapor degreasing tanks during normal operations, to measure crossdrafts in the vicinity of the vapor degreasing tanks, to use the measured crossdrafts and hood and source parameters to predict capture efficiency using a particular model, to compare predicted and measured capture efficiency, and to compare measured capture efficiencies and crossdrafts with observed degreaser activities. Local exhaust and general ventilation flow rates along with the physical dimensions of the work space and the degreaser were measured. There appeared to be reasonably good agreement between predicted and measured capture efficiency. However, poor agreement was obtained between predicted and measured efficiency for the interval efficiencies for each degreaser which could be due to turbulence, the effects of the cooling condenser on the degreaser, solvent being carried out of the degreaser to areas where the hood could not be expected to capture contaminants, and the variability in emission rate due to degreaser activity being inadequately taken into account in the predictive capture efficiency model.